Revert previous change to clear chunk list on the end of each tick, make it configurable instead.

Whilst the new behaviour was technically correct as it prevented the possibility of the chunk tick list actually increasing over time, it introduced a few issues, namely the fact that it slowed growth to unreasonable levels, and interfered with the values which server admins have finally tuned, and come to enjoy over the last few years.
If it is absolutely essential that growth be halted and ticking reduced as much as possible, the config option is there for power users.
If we wish to 'fix' this by default in the future, a new chunk ticking algorithm, which actually has meaningful config options should be designed.

By: md_5 <git@md-5.net>

CraftBukkit-Patches/0016-Fix-Mob-Spawning-Relative-to-View-Distance.patch

@@ -1,4 +1,4 @@
-From 77f77b800a6ffb71e6cf952e2f114b17c3e562f4 Mon Sep 17 00:00:00 2001
+From d9860352fadbcf7ba9dc05acdfa6f57bbb3fe2e7 Mon Sep 17 00:00:00 2001
 From: md_5 <md_5@live.com.au>
 Date: Fri, 21 Jun 2013 17:29:54 +1000
 Subject: [PATCH] Fix Mob Spawning Relative to View Distance
@@ -135,10 +135,10 @@ index f514b78..3f0dd70 100644
                                                                      continue label110;
                                                                  }
 diff --git a/src/main/java/org/spigotmc/SpigotWorldConfig.java b/src/main/java/org/spigotmc/SpigotWorldConfig.java
-index 97d56bd..47d8421 100644
+index 15b2ac8..49a5b7a 100644
 --- a/src/main/java/org/spigotmc/SpigotWorldConfig.java
 +++ b/src/main/java/org/spigotmc/SpigotWorldConfig.java
-@@ -127,4 +127,11 @@ public class SpigotWorldConfig
+@@ -131,4 +131,11 @@ public class SpigotWorldConfig
          viewDistance = getInt( "view-distance", Bukkit.getViewDistance() );
          log( "View Distance: " + viewDistance );
      }